This will doubtless seem a silly question to those who understand these things, but what head clearance do you need for a person to ride comfortably inside something like a tunnel?
I know much will depend on type of horse and height of rider, so I'm looking at a not-especially tall woman, say 5' 8" max but could be smaller, mounted on a palfrey, which I'm taking as around 15 or 16 hands (that never-knowingly-wrong (ha!) fount of all wisdom, Wikipedia, says the average size of the medieval horse was 12 to 14 hands, and I'm assuming a palfrey is -- or is in my world -- smaller than a courser, but bigger than a hobby) so that's 5 ft tall at the shouldery-bit** of the horse, right? She'd be riding old-fashioned side-saddle, if that makes a difference (perhaps not so erect as modern-style?) so would a tunnel height of 8ft be enough? Or does it need to be higher to allow more for the saddle itself plus the horse's gait -- only walking so no need to worry about rising trots or anything, but presumably there's some up-and-down motion still?
** excuse the highly specialised technical language